This invention relates to an image forming apparatus, and to a discharge system in an image forming apparatus such as a copying machine, for discharging image-formed sheets from an image forming section out of the apparatus body.
Copying machines are provided with a discharge system in order to discharge copy sheets following an image forming process. The discharge system is located downstream, with respect to the sheet transportation direction, of the image forming section, which comprises a photoconductive drum and associated elements. The discharge system is principally composed of a sheet-discharge transportation part, which transports image-formed sheets to a side wall of the apparatus body, a discharge roller mounted along the side wall, and a tray for receiving sheets discharged by the discharge roller.
Conventional discharge units work with a copy receiving tray projecting out from one side of the image forming apparatus, such that the overall area occupied by the apparatus is extensive, and a wide space is taken up.
Japanese Utility Model Laying-Open No. 40547/1981 discloses a copying machine having an interior copy receiving tray, inclined such that its front part is lower than its rear part. In this case, sheets transported from the image forming section drop along the slope of the tray and are discharged toward the front side of the apparatus body.
Copying machines disclosed in Japanese Utility Model Laying-Open No. 746/1982 and Japanese Patent Laying-Open No. 106269/1988 are also provided with interior copy receiving trays. The machines take up less space in their lengthwise direction because the copy receiving tray of either is contained within the apparatus body.
However, in the copying machine disclosed in Japanese Utility Model Laying-Open No. 40547/1981, smaller-sized sheets tend not to reach the front end of the tray since they drop along the slope only under their own weight. Thus, the ends of the sheets discharged do not register well, hindering working performance in subsequent handling.
In the copying machines disclosed in Japanese Utility Model Laying-Open No. 746/1982 and Japanese Patent Laying-Open No. 106269/1988, copy sheet removal is hampered by the fact that the sheets are received into the copy receiving tray as positioned in the apparatus body. In the copying machine disclosed in Japanese Patent Laying-Open No. 106269/1988, it is necessary to withdraw a retractable tray in order to remove discharged copy sheets. Moreover, checking the outcome of copied sheets during a copying operation is therefore not practicable, and many faulty copies may be developed. PG,4
Furthermore therein, there are extractable feed cassette and a discharge cassette which require respective guide rails, adding to the number of components and complicating the structure.
The discharge cassette itself occupies one of the cassette housings, subtracting from that the number of feed cassettes that can be simultaneously installed into the copying machine body.